Self-tapping floor screws are typically employed to securely fasten parts together in high-stress environments. For example, FIG. 1 depicts a portion of a flat-bed trailer 10 including a pair of generally steel cross-members 12, 14 and a plurality of generally wooden trailer floor decking planks 16 secured to the cross-members 12, 14 by a plurality of self-tapping floor screws 18. In constructing the trailer 10, screw holes 20 are pre-drilled in the cross-members 12, 14, and in the planks 16, but the holes 20 are not tapped (i.e., pre-threaded) to receive the screws 18. Instead, the screw holes 20 are tapped when the self-tapping screws 18 are first screwed into the originally untapped screw holes 20.
Because, as shown in FIG. 1, a sizeable number of screws 18 is used in a typical application of such screws 18, the aggregate time required to seat all of the screws 18 (i.e., to screw them completely into the corresponding holes 20) can be quite significant. The time required to insert a screw 18 in an untapped hole 20 (referred to hereinafter as the "total time") is further augmented by the inherent difficulty of locating the screws 18 in the untapped holes 20 to initiate the thread tapping process and by the substantial torque that must be generated to tap the screws 18 into the holes 20 in the steel cross-members 12, 14. To reduce the total time, prior-art self-tapping screws have been provided with slightly tapered ends to facilitate locating the tapered ends of the screws 18 in untapped holes 20 and to ease the tapping of the holes 20 by the screws 18. In addition, notches or flutes (described in more detail below) have been cut into the tapered ends of the screws 18 to aid the screws 18 in cutting or tapping threads into the holes 20 in the steel cross-members 12, 14. However, the total time for inserting these prior-art screws 18 into untapped holes 20 remains undesirably high. One prior-art self-tapping screw has five such flutes equally spaced around the circumference of the tapered end thereof.